Polymeric particles are frequently employed by interventional radiologists for the selective occlusion of blood vessels in the treatment of (but not limited to) hypervascular tumors such as leiomyoma uteri and vascular anomalies such as vascular malformations. However, current state of the art particles are beset with numerous drawbacks which limit market penetration for such products. The drawbacks include that the particles are not radiopaque. Thus, the clinician is not able to monitor placement of the particles radiographically. The result is that complications of embolization, such as reflux with non-target embolization and through embolization are not detectable. Current approaches to this problem include dispersing the particles in a medium that includes a contrast agent that is visible radiographically. This leads to its own complications however. Contrast-induced nephropathy occurs in about seven percent of patients exposed to contrast agents. Contrast-induced nephropathy is characterized by acute renal injury which can lead to renal failure. Exposure to contrast agents is the third most common cause of hospital acquired renal failure. Additionally, the degradation of the particles currently in use cannot be controlled. The ability to choose particles that are either non-degradable or that have differing degrees of degradability allows for more treatment options for the various lesions that are amenable to embolization. Use of particles that degrade with time may allow for revascularization of the occluded blood vessel after the treated lesion is gone resulting in recovery of blood flow to normal tissue. This would be desired in instances such as the treatment of gastrointestinal hemorrhage. In other instances, use of a non-degradable particle prevents revascularization of the underlying vessel. This would be desired in vascular lesions such as vascular malformations.
Thus, what are needed are improved embolic particles that limit the addition of a contrast agent for radiographic imaging and whose degradation may be controlled.